Device for taking samples from loose ground layers

ABSTRACT

A coring device comprising a tubular body provided at its lower end with a crown type drill bit. This crown bit has a central bore obturated by a plugshaped element. Under remote control, and under the action of a pressurized gas housed in a chamber, a core barrel of small wall thickness slidable along the plug-shaped elements is pushed downwardly through the annular space between the internal wall of the crown bit and the external wall of the plug, from a first position wherein this core barrel is locked in the tubular body to a second position in which the core barrel projects beyond the crown bit and penetrates the ground.

Castel et a1.

[ Mali". 11, 1975 DEVECE FOR TAKING SAMPLES FROM LOOSE GROUND LAYERS Inventors: Yvon Castel, Le Pecq; Andre Castela, Mesnil'Le Roi, both of France lnstitut Francais Du Petrole Des (:arburants et Lubriiiants, Rueil-Malmaison, France Filed: Feb. 12, 1974 Appl. No.: 441,895

Assignee:

Foreign Application Priority Data Feb. 20, 1973 France 73.06000 References Cited .UNITED STATES PATENTS Baker ..'l75/235 Higgins 2,541,785 2/1951 Smith 175/233 3,047,081 7/1962 Pitcher 175/248 X 3,136,376 6/1964 Robinsky 175/238 X 3,163,241 12/1964 Daigle ct 211.... 175/20 X 3,349,857 10/1967 Hildebrandt 175/250 3,438,452 4/1969 Bernard et a1. 175/20 X 3,830,320 8/1974 Van Der Wijden 175/238 Primary Examiner-David H. Brown Attorney, Agent, or Firm-Craig & Antonelli [57] ABSTRACT A coring device comprising a tubular body provided at its lower end with a crown type drill bit.

This crown bit has a central bore obturated by a plugshaped element. Under remote control, and under the action of a pressurized gas housed in a chamber, a core barrel of small wall thickness slidable along the plug-shaped elements is pushed downwardly through the annular space between the internal wall of the crown bit and the external wall of the plug, from a first position wherein this core barrel is locked in the tubular body to a second position in which the core barrel projects beyond the crown bit and penetrates the ground.

18 Claims, 5 Drawing Figures PATENTED MARI 1 I975 SHEET 2 OF FIGJB PATENTEB MARI H975 sum 3 o g FIG.2B

FIG.2A

. '1 A I DEVICE FOR TAKING SAMPLES FROM LOOSE GROUND LAYERS The present invention relates to a device, more particularly a coring device, for collecting from friable or loose ground layers, unaltered ground samples.

At the present time, conventional coring devices for collecting ground samples or cores from loose ground layers, comprise a tubular body housing a core barrel of small wall thickness provided with a cutting member at its'lower end.

The coring operation is achieved by driving the corebarrel into the ground,for example by the action of an explosive charge.

Such explosion -actuated coring devices suffer from certain drawbacks in some cases of applications, the most important of which are listed hereinfter:

high exploitation cost (as a consequence of the high cost ofthe explosive cartridges),

impossibility of collecting a sample from a deep ground layer without necessarily also collecting samples from the overlaying ground layer.

The main object of the present invention is accordingly to provide a coring device which does notsuffer fromthe drawbacks of the prior coring devices used up to now for collecting unaltered samples of loose ground layers.

In particular, the coring device according to the invention is adapted to traverse the ground layers by penetration of the core barrel therethrough, without 'collecting any ground samples or core before reaching the depth at which it is desired to take a core.

ln a' particular embodiment of the invention it is possible to reintroducethe core barrel into the coring de vice after removal of the ground sample or core housed in the core barrel.

The device according to the invention for collectin groundsamples or cores from loose ground layers comprises a rigid tubular body housing a'core barrel slidable therein under the action of remotely controlled internal wall of said body and the external wall of said gun tube, said ducts opening out in the immediate vicinity of said drill bit, thereby permitting the flow 0f the flushing fluid from said source of fluid, and a heavy main piston means placed abovesaid core barrel and integral therewith, said piston means and said core barrel being slidable in said gun tube.

The propulsion or driving means comprises a chamber containing pressurized fluid and communicating through an orifice with the interior of said gun tube, a controlled member which, in said drilling position of the device, obturates said orifice, thereby preventing the flow of the fluid from said chamber to said gun tube which would exert on said main piston means a force releasing said core barrel from said locking means, thereby suddenly propulsing said core barrel from said first position to said second position.

The invention will be properly understood and its ad vantages become apparent from the following description of embodiments illustrated by the accompanying drawings wherein:

FIG. 1A and 1B respectively show, in axial cross section, the upper and the lower part of a coring device acpropulsion means, from a first position, in'which said f core barrel is secured by locking means inside said tubular body, to a second'position in which saidcore barrel at least-partially projects beyond'said tubular body and penetrates. the loose ground layers. The tubular body can b e connected to a source of drilling fluid and to driving means for driving in rotation said tubular body and the device comprises, in combination, a

nected to said core barrel and maintained substantially cording to the invention,

FIGS. 2A and 2B diagrammatically illustrate the operation of the coring device according to the invention, and FIG. 3 shows an axial cross section of the device of the invention equipped with means for reintroducing the core barrel into this device after a coring operation has been performed.

FIGS. 1A and 1B diagrammatically show a cross section of a coring device according to the invention.

In these figures, reference numeral 1 designates the tubular body of the coring device, formed of a rigid tubular assembly which may comprise one or more interconnectedtubular elements.

A crown-type drill bit 2 is coupled to the lower part of the tubular body 1, through a screwing 3 (FIG. 1B).

The tubular body I may be coupled to means (not I ally therewith.

at the level of said drill bit,.the lower end of said core v bore in'said first position, which thus constitutes a position of full bore drilling of the device.

According" to an-embodiment of the invention, the device comprises a gun tube integral with said tubular body and housed therein, ducts provided between the This gun tube 5, made integral with the tubular body 1 through a screwing (not illustrated), has longitudinal grooves on its external wall, along a direction parallel tothe axis of the coring device, forming ducts 6 between the internal wall of the body 1 and the external wall of the gun tube 5.

Within the gun tube Sthere is housed a core barrel 7 (FIG. 1B) of small wall thickness, whose external diameter is slightly smaller than the internal diameter of the gun tube 5. Acutting member 8 extends at its lower end the core barrel 7. This cutting member and the core barrel are of such diameter as to be slidable in the central bore of the crown bit 2. At its lower end, the cutting member 8 is provided with ground cutting elements, such as teeth 15, whose usefulness will appear hereinunder.

A heavy piston 9 is secured at the upper end of the core barrel 7. This piston is mounted in the gun tube 5 slidable between an upper position and a lower position, driving along therewtih the core barrel 7.

The piston 9 is held in its upper position (FIG. 1A) through a locking device formed of one or more balls 21 which are radially displaceable in housings 21a, under the action of springs 22 and which partially penetrate in a circular groove 23 of the piston 9, so as to make the latter solid with the tubular body 1. The groove 23 has a V-shaped cross section.

The piston 9 is traversed by an axial bore opening at its lower end, in the core barrel 7.

Inside the core barrel and coaxially therewith, is housed a tubular sheath 10 (FIG. 18), made for example of a plastic material, which protects the collected ground sample or core.

At the upper part of the core barrel 7, calibrated valves, diagrammatically shown at 11, permit the flow of any fluid, whether gaseous or liquid, through the channels 12, from the interior of the sheath 10 to the exterior of the core barrel.

Inside the cutting body 8 and at the level of the crown bit 2, there is housed a plug-shaped drilling element or obturator element 13 having a cutting face 14 for drilling into the ground, thus preventing the formation of a core in the position shown in FIG. 1A and 1B of the coring device.

The plug-shaped element 13, the cutting member 8 and the crown bit 2 are fast in rotation with one another through a double cotter-pin 16, which is integral with the cutting member 8 and cooperates on the one hand with a first longitudinal groove 17 provided in the plug-shaped element 13 and, on the other hand, with a longitudinal groove 18 provided in the crown bit 2,

these grooves being parallel to the axis of the coring device.

The plug-shaped element 13 is secured to the lower end of a supporting rod 19, coaxial with-the coring device. This rod traverses the piston 9, passing through the axial bore 20.

Suitable means 24 provides for sealing of the bore 20, around the supporting rod 19.

The upper part of the coring device houses control means for this device and suspension means for the supporting rod 19. The assembly comprises a cylindrical element 25 provided with three flanges 25a, 25b and 250, this cylindrical element being made integral with the body 1 and with the gun tube 5, for example by screwing means, which have not been shown .for sake of clarity of the drawing.

The supporting rod 19 passes through a bore 26 of the cylindrical element 25 and its upper part, provided with a piston 27, is located in a cylindrical chamber 28 filled with a fluid, such as a gas, at a pressure P This fluid pressure is applied to the lower face of piston 27 and maintains the supporting rod 19 in its upper position, the piston 27 being then in abutment against a shoulder of the cylindrical element 25. A spring 29 is placed between the piston 27 and the bottom of the cylindrical chamber 28. Means 34 provides for the sealing between the bore 26 and the supporting rod 19. A device, such as a valve, diagrammatically shown at 35, enables the fluid to flow from chamber 28, into the channels 6, when the pressure in this chamber becomes greater than a predetermined value. Another valve (not shown) permits the introduction of pressurized fluid into the cylindrical chamber 28. The piston 27 and the cylindrical chamber 28 form the suspension means for the supporting rod 19.

The control means for the coring device comprises an annular chamber 31 limited by the gun tube and the two flanges 25a and 25b. The sealing of this chamber in which a pressurized gas is introduced through a valve 52, is achieved by sealing means 32 and 33. Through device, such as a calibrated valve 53, the pressure in the chamber 31 can be limited to a predetermined value P The chamber 31 may be put into communication with the free space between the piston 9 and the lower flange 25a through a device, such as a valve which comprises a piston 36 located in a bore 36a traversing the flange 25a, this piston being connected through a connecting rod 37 to another piston 38 which is slidable in a bore 39 arranged in an intermediary flange 25b, the two bores 36a and 39 having the same axis.

A calibrated spring 40 is placed between the flange 25b and a shoulder 37a of the connecting rod 37.

The fluid housed in chamber 31 exerts its pressure on the pistons 36 and 38, the cross section S of piston 38 being greater than the cross section s of piston 36.

The piston 38 extends through a control rod 41 which, under the action of the gas pressure exerted on piston 38, comes into abutment, in its upper position. against a hinged latch 42'solid with the flange 25b. A releasing rod 43 holds the hinged latch 42 in the position illustrated in FIG. 1A.

The releasing rod 43 is integral with the rod of a piston 44 housed in a cylindrical bore 45 of the upper flange 250. When no pressure is exerted on piston 44, the latter is held in its upper position under the action of a spring 46.

The flange 250 is provided with internal vertical ducts 47 which communicate with spaces 48 housing the balls 49. Over the flange 25c is placed a cover 50 which obturates the bore 28 at its upper end and puts in communication the cylindrical bore 45 and the ducts 47 with the upper end of the body 1, through orifices 51.

As apparent from FIG. 1A, the space between the flanges 25b and 25c communicates with the ducts 6.

The operation of the coring device will be described hereinunder with reference to FIGS. 1A, 1B and FIGS. 2A and 2B which diagrammatical illustrate a coring operation performed with this device.

The elements of the coring device are in the position illustrated in FIGS. 1A and 1B, i.e. the piston '9 is held in its upper position by the locking balls 21, the plugshaped element 13 and the cutting member 8 being placed at the level of the crown bit 2, so as to prevent the formation of a core within the central bore of the tool.

Through a not illustrated device, such as a valve, a pressurized gas, for example pressurized air, is injected into the cylindrical chamber 28. Its pressure P, is, for example, 120 bars and the device 35 has been calibrated for a pressure P, of, say, 400 bars. The piston 27 bears against the shoulder 30 of the cylindrical element 25.

A pressurized gas, for example air, is injected through the device 52, into the annular chamber 31. Its

9, of the resistance of the grounds to the penetration of the core barrel and, when the coring device is used for collecting cores from submerged ground layers, this value of P is also a function of the hydrostatic pressure prevailing at the water bottom.

The pressurized air filling the chambers 28 and 31 may be supplied by an air compressor before the coring device is put into operation. The surface S of the piston 38 being greater than the surface s36, the rod 41 is subjected to an upward force and comes into abutment against the hinged latch 42. In this position the pistons 36 and 38 provide for sealing of the annular chamber 31.

It will be assumed in the following that a ground sample or core must be taken from a loose ground layer at a depth H, relative to the superficial ground layer, greater than the length of the coring device.

In a first step, the coring device is driven in rotation. Under the action of the centrifugal force the balls 49 take the position shown in dotted line in FIG. 1A, thereby uncovering the orifices 47.

A drilling fluid is then injected through the coring device. This fluid flows along the path indicated by the arrows in FIGS. 1A and 1B, i.e. through the ducts 51, the orifices 47 and then through the ducts 6 before irrigating the lower face of the drill bit which attacks the ground. The pressure of the drilling fluid has such a value that the piston 44 cannot be displaced against the action of the spring 46. Since the cotter pin 16 (FIG. 18) makes the cutting member 8 fast in rotation with the plug-shaped drilling element 13, the coring device thus works as a full bore drilling device in this position. The first operating step is accordingly a drilling step which is continued until the coring device reaches the depth H at which a core has to be collected.

At that time the circulation of drilling fluid is discontinued and the rotation of the device is then stopped. The balls 49 then obturate the orifices 47.

In order to perform a coring operation, the pressure of the drilling fluid is increased. This fluid then'exerts its pressure on the piston 44 which is displaced in the cylinder 45 against the action of return means, such as the spring 46. The rod of piston 44 drives therewith the releasing rod 43 which then releases the latch 42. The latter is then free to pivot about its axis.

.Under the action of the pressure of the gas housed in I the annular chamber 31, the piston 38 moves upwardly and vertically, thereby compressing the spring 40. During this movement, the piston 38 drives the piston 36 to which it is connected through the rod 37. The piston 36 then uncovers the orifice of the cylinder 36a and the pressurized gas housed in chamber 31 rapidly escapes through this aperture, exerting its pressure on the upper face of piston 9.

This piston is then subjected to a sudden, downward force which results in the unlocking of piston 9, causing the balls 23 to penetrate their respective housings and the piston 9 to move toward the lower part of the coring device, thereby driving along therewith the core 7 barrel 7 and the cutting member 8.

The core barrel 7 penetrates the ground layer under the action of the force transmitted through piston 9, against the resistance opposed by the ground to this penetration (FIG. 23).

Meanwhile, the pressure in the annular chamber 31 has decreased. When its value has reached a predetermined limit, for example 25 bars, the spring 40 moves the assembly of the two pistons 36-38, preventing other fluids, such as the drilling fluid, from penetrating into this chamber.

In order to limit the action of the pressurized air on piston 9, grooves 54 provided in the gun tube 5, at some distance from the flange 25a, communicate with the ducts 6, thereby allowing the pressurized gas to escape when the upper face of piston 9 has reached the groove 54.

During the penetration of the core barrel into the ground the calibrated valves 11 enable any fluid to escape from the sheath l0 protecting the collected core.

After the propulsion of the core barrel, and in the case where the resistance to penetration of the ground is lower than the force of propulsion of the core barrel 7, the piston 9 hits the plug 13. For preventing the destruction of the latter, the shock is absorbed or damped through the piston 27 which is displaced against the action of the spring 29, the pressure of the pressurized air in chamber 28 being kept at a value at most equal to 400 bars by means of a device 35, such as a valve.

The device is then raised to the surface by exerting a vertical traction on the drill string, the core being held in the core barrel by core catchers 55.

During the raising of the core device, the core barrel remains outside the tubular body 1. The core is removed by unscrewing the coring device and is stored in its protective sheath 10.

After a new protective sheath has been positioned and the elements of the coring device screwed together, the coring device may be used again in the same manner as just indicated.

FIG. 3 shows another embodiment with the upper end of the coring device equipped with means permitting the reintroduction of the core barrel into the tubular body 1, after the core removal.

This drawing shows a cross-sectional view of the coring device along plane which is'different of the sectional plane in FIG. 1A, but all the elements constituting the device according to FIGS. 1A and 1B are also present injthe embodiment of FIG. 3 although they are not shown. I

In this other embodiment the piston 27 is provided with a central bore wherethrough the supported rod 19 is slidable. A duct 56 having a calibrated small-- diametered cross-section, opens on both faces of the piston 27, thereby. establishing a communication between the two spaces on both sides of the piston 27.

The means for reintroducing the core barrel 7 into the tubular body of the coring device comprises, for example, two jacks 57 integral with the body 1 and whose rods are radially displaceable with respect to the tubular body 1. These two jacks are located above the piston 27. The cylinders of the jacks 57 communicate with the chamber 31 through ducts 58. By this way the pressure of the gas housed in the chamber 31 is exerted on the pistons of the jacks 57, thereby displacing the rods of these jacks toward the axis of the coring device against the antagonistic action of springs 59.

In this position of the jacks 57, a shoulder 60 of the supporting rod 19, in contact with the rods of the jacks 57, prevents any upward axial displacement of the rod 19.

Above the jacks 57, the end of the rod 19 is integral with a piston 61, slidable in a cylinder 62 extending the cylindrical chamber 28.

Through the calibrated duct 56, the gas housed in the cylindrical chamber 28 exerts its pressure on the piston 61 which keeps the shoulder 60 in contact with the rods of the jacks 57, in which position the plug 13 (FIG. 1B)

is at the level of the crown bit 2.

The cylinder 62 has a length which is at least equal to that of the core-barrel 7, this cylinder is located in a bore of the shaft 63 of the means 64 for driving the tubular body I, if this means is a downhole motor.

The upper end of the cylinder 62 is obturated by a plug 65 and communicates with a duct 66 which is connected to a chamber 67.

The latter communicates with the exterior of the coring device through a duct 68 and a non-return valve 69.

The chamber 67 houses a plug 72 traversed by a duct 70.

In a first position of the plug 72, illustrated by FIG. 3, the ducts 66 and 68 communicate with each other through chamber 67, while in a second position, which is reached by displacement of the plug against the action of the spring 71, the duct 66 communicates exclusively with the duct 70 of the plug 72.

The operation of the reintroducing means is described hereinafter:

The device being in the position illustrated by FIG. 3, the drilling and then the coring steps are performed as above indicated.

During this last step, the piston 27 still operates as a damping means, since the channel 56 is of narrow cross-section.

The core barrel having been driven into the ground layers, the gas pressure in the chamber 31 and consequently the gas pressure in the jacks 57 has reached its minimum value.

The springs 59 exert on the jacks 57 a force which is greater than that resulting from the gas pressure. The rods of the pistons of jacks 57 are displaced radially,

moving away from the axis of the coring device and releasing the supporting rod 19. v

The pressure of the fluid in the cylindrical chamber 28 is exerted on the reintroduction piston 61 which is displaced in the cylinder 62, driving along therewith the supporting rod 19, integral with the plug 13 which is then in contact with the lower face of the main piston 9 (FIG. 23). From the foregoing, it is apparent that the core .barrel housing the collected ground sample or core, penetrates into the gun tube 5.

During the displacement of the reintroduction piston 61, the fluid housed in the upper part of the cylinder 62 is expelled into the annular space of the drilled well through the ducts 66 and 68 and the non-return valve 69.

The pressure of the fluid in the cylindrical chamber 28 is of course higher than the pressure of the drilling fluid in the annular space between the bore'wall and the coring device.

After removal of the core, the supporting rod may be placed back to its initial position by injecting into the upper part of the cylinder 62 a gas such as pressurized air.

The operation is then as follows:

A mouthpiece connected to a source of pressurized fluid displaces the plug 72 in its housing, interrupting the communication between the ducts 66 and 68 and permitting the injection of a pressurized fluid into the upper part of the cylinder 62, through the orifice 70 which communicates with the duct 66.

The pressurized gas is introduced into the annular chamber 31, thereby displacing the rods of the jacks 57 toward the axis of the coring device.

The chamber 28 is then pressurized as above indicated. The coring device is then ready for a new coring operation.

Modifications may be made without departing from the scope of the present invention. For example, it will be possible to use the damping piston 27 as a reintroduction piston, by suppressing the shoulder 31 and the duct 56, the piston 27 being displaceable in the cylinder 62 after the rods of the jacks 57 have been subjected to the action of the spring 59.

We claim:

1. A device for sampling cores from loose ground layers, comprising a rigid tubular body, a core barrel housed in said tubular body and slidable therein under the action of controlled propulsion means, from a first position, in which said core-barrel is secured through locking means to said tubular body, to a second position in which said core barrel at least partially projects beyond said tubular body and penetrates the loose ground layer, this rigid tubular body being adapted to be connected to a source of drilling fluid and to means for driving in rotation said tubular body and comprising, in combination, a crown-type drill bit provided with a bore through which said core barrel can slide from said first position to said second position, an obturator means for said core barrel, said obturator means being slidably mounted in said core barrel and being provided at its lower part with ground cutting elements, said obturator means being further connected to said core barrel and maintained substantially at the level of said drill bit in said first position of said core barrel, the lower end of said core barrel being also provided with ground cutting elements and being also located at the level of said drill bit in said first position of said core barrel, said lower end and said obturator means thus cooperating with said core barrel for obturating the bore of the drill bit by the cutting elements, thereby preventing the formation of a core within said bore in said first position which thus defines a position of full bore drilling of the device.

2. A device according to claim 1, wherein said obturating means is constituted by a plug-shaped drill bit element having a cylindrical shape and comprises means for making said drill bit, said core barrel and said plugshaped element in the drilling position of the device, fast in rotation.

3. A device according to claim 2, wherein said means for making fast in rotation includes at least a cotter pin integral with the core barrel, said pin being slidable on the one hand in a longitudinal groove provided in the cylindrical wall of said plug-shaped element and, on the other hand, in a longitudinal groove provided in the cylindrical wall of the bore of said drill bit.

4. A device according to claim 1, wherein said obturating means is connected to said tubular body through suspension means comprising a suspension rod coaxial with the device, a first end of said rod being integral with said obturating means and the second end being connected to said body through resilient means.

5. A device according to claim 4, wherein said second end of the suspension rod is integral with an auxiliary piston which is slidable in a cylinder integral with said body and filled with a compressible fluid which exerts a force on said auxiliary piston in contact with a shoulder of said cylinder and a spring is placed between said auxiliary piston and said cylinder.

6. A device according to claim 4, comprising means for reintroducing said core barrel into said gun tube after removing a core from said core barrel, said means for introducing actuating said suspension rod.

7. A device according to claim 6, wherein said suspension means comprises an auxiliary piston which is displaceable in a cylinder integral with said tubular body, said cylinder being filled with a fluid under pressure which keeps said auxiliary piston in an upper position, said suspension rod being provided with a shoulder adapted to come into abutment against said auxiliary piston and to displace it against the action of the fluid pressure, said resilient means being constituted by spring means placed between said auxiliary piston and its cylinder, and said means for reintroducing comprises a second locking means bearing against said shoulder of said suspension rod, said locking element maintaining said suspension rod in a position in which said obturating means is at the level of said drill bit, said second locking means being adapted to release said suspension rod when said core barrel has penetrated the ground layers, and handling means for axial dis placement of said suspension rod.

8. A device according to claim 7, wherein said handling means are constituted by ajack integral with said tubular body and whose piston is connected to said suspension rod, said auxiliary piston having a calibrated bore opening out on both of the parallel faces of said auxiliary piston, said calibrated bore establishing a communication between the cylinder in which said auxiliary piston is displaceable and one ofthe chambers limited by the piston of the handling means, the other of said chambers being connected through a duct to an element for sequentially connecting said other chamber with a source of pressurized fluid or with the external space surrounding the device.

9. A device according to claim 7, wherein said second locking means is formed by at least one locking jack placed radially relative tov the axis of the device and communicating with said chamber through at least one duct, so that, under the action ofthe pressure of the gas housed in said chamber, the rod of said locking jack is displaced against the antagonistic action of resilient means, toward the device axis and cooperates with said shoulder of said suspension rod to keep saidrod in the position in which said obturating means is located substantially at the level of said drill bit.

10. A device according to claim 1 comprising a gun tube integral with said tubular body and housed therein, ducts provided between the internal wall of said body and the external wall of said gun tube, said ducts opening out in the immediate vicinity of said drill bit, thereby permitting the flow of the flushing fluid from said source of fluid, and a heavy main piston placed above said core barrel and integral therewith, said piston and said core barrel being slidable in said gun tube.

11. A device according to claim 10, wherein said propulsion means comprises a chamber housing a pressurized fluid and communicating through an orifice with the interior of said gun tube and a controlled member which, in said drilling position of the device, obturates said orifice, thereby preventing the fluid from flowing from said chamber into said gun tube, which would exert on said main piston a force releasing said core barrel from said locking means and thereby propulsing it from said first position to said second position.

12. A device according to claim 11, wherein said chamber is filled with a gas under a determined pressure.

13. A device according to claim 12, wherein said gas is pressurized air.

14. A device according to claim 11, wherein said controlled member comprises a differential piston including an obturation piston slidable through said orifree for opening or closing this orifice and a control piston integral with said obturation piston and displaceable in a bore, the fluid in said chamber exerting its pressure on said differential piston for moving it, against the antagonistic action of calibrated return means, toward a position of opening of said orifice when the device is in its drilling position.

15. A device according to claim 14, wherein said calibrated return means comprises calibrated spring means placed between said differential piston and said chamber, said calibrated spring means displacing said differential piston to its position of closure when the pressure in the fluid has reached, while decreasing, a predetermined value corresponding to the calibration of said calibrated spring means.

16. A device according to claim 14, comprising means for controlling said controlled member, said means for controlling being adapted to cause the opening of said orifice only when the device is not driven in rotation, by action on said locking means.

17. A device according to claim 16, wherein said control member comprise means for selecting the operation of the device, said selecting means comprising a recess which communicates, through at least one opening, with said ducts and a ball, displaceable within said recess for obturating said opening when said tubular body is not driven in rotation, and for uncovering said Opening under the action of a centrifugal force when the device is in its drilling position and is driven in rotation, said control member further including control jack means connected through a duct to the inlet of the drilling fluid, said jack means having a piston which is displaceable against the antagonistic action of spring means, under the action of an increase in the drilling pressure occurring in the absence of rotation of the device, for actuating a control rod which releases said differential piston from said locking means.

18. A device according to claim 17, wherein said locking means consists ofa rod integral with said differential piston, said rod bearing, in said drilling position of the device, against a hinged latch which is held in a locking position through said control rod.

Q UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 112 Page 1 of 2 DATED March 11, 1975 Q INVENTOR(S) Yvon Castel, et a1,

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, lines 54 and 55, which now read said obturator means being further connected to said core barrel,

should now read;

. said obturator means being further connected to said rigid tubular body,

Column 8, Claim 1, lines 32 and 33, which now read:

. said obturator means being further connected to said core barrel.

should now read;

Q -said obturator means being further connected to said rigid tubular body,

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 870, 112 Page 2 of 2 DATED March 11, 1975 INVENTOR(S) Yvon Castel et a1 It is certified that error appears in the above-identified patent and that said Letters Patent 7 are hereby corrected as shown below:

Column 8, Claim 1, Lines 32 and 33, which now read:

". said obturator means being further connected to said core barrel should now read:

-- said obturator means being further connected to said rigid tubular body Signcd and Scaled this Arrest:

SIDNEY A. DIAMOND Anem'ug Oflicer Commissioner of Patents and Trademarks 

1. A device for sampling cores from loose ground layers, comprising a rigid tubular body, a core barrel housed in said tubular body and slidable therein under the action of controlled propulsion means, from a first position, in which said core-barrel is secured through locking means to said tubular body, to a second position in which said core barrel at least partially projects beyond said tubular body and penetrates the loose ground layer, this rigid tubular body being adapted to be connected to a source of drilling fluid and to means for driving in rotation said tubular body and comprising, in combination, a crown-type drill bit provided with a bore through which said core barrel can slide from said first position to said second position, an obturator means for said core barrel, said obturator means being slidably mounted in said core barrel and being provided at its lower part with ground cutting elements, said obturator means being further connected to said core barrel and maintained substantially at the level of said drill bit in said first position of said core barrel, the lower end of said core barrel being also provided with ground cutting elements and being also located at the level of said drill bit in said first position of said core barrel, said lower end and said obturator means thus cooperating with said core barrel for obturating the bore of the drill bit by the cutting elements, thereby preventing the formation of a core within said bore in said first position which thus defines a position of full bore drilling of the device.
 1. A device for sampling cores from loose ground layers, comprising a rigid tubular body, a core barrel housed in said tubular body and slidable therein under the action of controlled propulsion means, from a first position, in which said corebarrel is secured through locking means to said tubular body, to a second position in which said core barrel at least partially projects beyond said tubular body and penetrates the loose ground layer, this rigid tubular body being adapted to be connected to a source of drilling fluid and to means for driving in rotation said tubular body and comprising, in combination, a crown-type drill bit provided with a bore through which said core barrel can slide from said first position to said second position, an obturator means for said core barrel, said obturator means being slidably mounted in said core barrel and being provided at its lower part with ground cutting elements, said obturator means being further connected to said core barrel and maintained substantially at the level of said drill bit in said first position of said core barrel, the lower end of said core barrel being also provided with ground cutting elements and being also located at the level of said drill bit in said first position of said core barrel, said lower end and said obturator means thus cooperating with said core barrel for obturating the bore of the drill bit by the cutting elements, thereby preventing the formation of a core within said bore in said first position which thus defines a position of full bore drilling of the device.
 2. A device according to claim 1, wherein said obturating means is constituted by a plug-shaped drill bit element having a cylindrical shape and comprises means for making said drill bit, said core barrel and said plug-shaped element in the drilling position of the device, fast in rotation.
 3. A device according to claim 2, wherein said means for making fast in rotation includes at least a cotter pin integral with the core barrel, said pin being slidable on the one hand in a longitudinal groove provided in the cylindrical wall of said plug-shaped element and, on the other hand, in a longitudinal groove provided in the cylindrical wall of the bore of said drill bit.
 4. A device according to claim 1, wherein said obturating means is connected to said tubular body through suspension means comprising a suspension rod coaxial with the device, a first end of said rod being integral with said obturating means and the second end being connected to said body through resilient means.
 5. A device according to claim 4, wherein said second end of the suspension rod is integral with an auxiliary piston which is slidable in a cylinder integral with said body and filled with a compressible fluid which exerts a force on said auxiliary piston in contact with a shoulder of said cylinder and a spring is placed between said auxiliary piston and said cylinder.
 6. A device according to claim 4, comprising means for reintroducing said core barrel into said gun tube after removing a core from said core barrel, said means for introducing actuating said suspension rod.
 7. A device according to claim 6, wherein said suspension means comprises an auxiliary piston which is displaceable in a cylinder integral with said tubular body, said cylinder being filled with a fluid under pressure which keeps said auxiliary piston in an upper position, said suspension rod being provided with a shoulder adapted to come into abutment against said auxiliary piston and to displace it against the action of the fluid pressure, said resilient means being constituted by spring means placed between said auxiliary piston and its cylinder, and said means for reintroducing comprises a second locking means bearing against said shoulder of said suspension rod, said locking element maintaining said suspension rod in a position in which said obturating means is at the level of said drill bit, said second locking means being adapted to release said suspension rod when said core barrel has penetrated the ground layers, and handling means for axial displacement of said suspension rod.
 8. A device according to claim 7, wherein said handling means are constituted by a jack integral with said tubular body and whose piston is connected to said suspension rod, said auxiliary piston having a calibrated bore opening out on both of the parallel faces of said auxiliary piston, said calibrated bore establishing a communication between the cylinder in which said auxiliary piston is displaceable and one of the chambers limited by the piston of the handling means, the other of said chambers being connected through a duct to an element for sequentially connecting said other chamber with a source of pressurized fluid or with the external space surrounding the device.
 9. A device according to claim 7, wherein said second locking means is formed by at least one locking jack placed radially relative to the axis of the device and communicating with said chamber through at least one duct, so that, under the action of the pressure of the gas housed in said chamber, the rod of said locking jack is displaced against the antagonistic action of resilient means, toward the device axis and cooperates with said shoulder of said suspension rod to keep said rod in the position in which said obturating means is located substantially at the level of said drill bit.
 10. A device according to claim 1, comprising a gun tube integral with said tubular body and housed therein, ducts provided between the internal wall of said body and the external wall of said gun tube, said ducts opening out in the immediate vicinity of said drill bit, thereby permitting the flow of the flushing fluid from said source of fluid, and a heavy main piston placed above said core barrel and integral therewith, said piston and said core barrel being slidable in said gun tube.
 11. A device according to claim 10, wherein said propulsion means comprises a chamber housing a pressurized fluid and communicating through an orifice with the interior of said gun tube and a controlled member which, in said drilling position of the device, obturates said orifice, thereby preventing the fluid from flowing from said chamber into said gun tube, which would exert on said main pistOn a force releasing said core barrel from said locking means and thereby propulsing it from said first position to said second position.
 12. A device according to claim 11, wherein said chamber is filled with a gas under a determined pressure.
 13. A device according to claim 12, wherein said gas is pressurized air.
 14. A device according to claim 11, wherein said controlled member comprises a differential piston including an obturation piston slidable through said orifice for opening or closing this orifice and a control piston integral with said obturation piston and displaceable in a bore, the fluid in said chamber exerting its pressure on said differential piston for moving it, against the antagonistic action of calibrated return means, toward a position of opening of said orifice when the device is in its drilling position.
 15. A device according to claim 14, wherein said calibrated return means comprises calibrated spring means placed between said differential piston and said chamber, said calibrated spring means displacing said differential piston to its position of closure when the pressure in the fluid has reached, while decreasing, a predetermined value corresponding to the calibration of said calibrated spring means.
 16. A device according to claim 14, comprising means for controlling said controlled member, said means for controlling being adapted to cause the opening of said orifice only when the device is not driven in rotation, by action on said locking means.
 17. A device according to claim 16, wherein said control member comprise means for selecting the operation of the device, said selecting means comprising a recess which communicates, through at least one opening, with said ducts and a ball, displaceable within said recess for obturating said opening when said tubular body is not driven in rotation, and for uncovering said opening under the action of a centrifugal force when the device is in its drilling position and is driven in rotation, said control member further including control jack means connected through a duct to the inlet of the drilling fluid, said jack means having a piston which is displaceable against the antagonistic action of spring means, under the action of an increase in the drilling pressure occurring in the absence of rotation of the device, for actuating a control rod which releases said differential piston from said locking means. 